Resealable envelope

ABSTRACT

A resealable envelope comprising a flexible plastic back sheet, a backing adhesive applied on a back surface of the flexible plastic back sheet to attach the envelope to a package, a flexible plastic front sheet attached to the back sheet at their respective side edges and bottom edges, a flexible closure flap being adhered directly to the front surface of the back sheet at their respective top edges via a permanent adhesive and overlapping said front sheet, and a resealable adhesive located proximal to the top edge of the front sheet such that the resealable adhesive is capable of fastening said closure flap to the front sheet forming a resealable closure.

FIELD OF THE INVENTION

The instant invention relates to a resealable, flexible plastic envelopehaving superior durability to those of the prior art. In particular, theclosure flap of the instant invention can be repeatedly opened andresealed without damaging the integrity of the envelope.

BACKGROUND OF THE INVENTION

Adhesive type closure arrangements have been used to seal and/or closeplastic bags such as those used for sandwiches, garbage containers, andother household uses. For example, U.S. Pat. No. 4,519,095 to Claytondescribes a resealable flexible thermoplastic bag wherein the closurecomprises at least one female channel member or strip-affixed to the bagand having a pressure sensitive adhesive layer on an internal portion ofthe channel strip such that the thickness of the adhesive layer is lessthan the interior depth of the walls of the channel strip. Duringshipment and storage the walls of the channel hold the pressuresensitive adhesive layer away from adjacent surfaces to preventinadvertent sticking. Sealing of the bag is achieved by contacting thechannel strip with a surface of the bag and exerting pressure along thestrip whereby the pressure sensitive adhesive is contacted with asubstantially flat portion of the surface and adhered thereto.

Clayton discloses a resealable plastic bag containing a channel with theadhesive layer positioned on a flap of the bag, a channel with theadhesive positioned on the body of the bag over which the flap willfold, and two female channel strips positioned on opposite sides of abag opening to affect a double seal by pressing the two channels intocontact such that one wall or bead of each channel is contacted by theadhesive layer in the opposing channel.

Other patents disclosing resealable, flexible plastic bags include U.S.Pat. Nos. 5,791,783 and 5,783,012, both to Porchia et al.; U.S. Pat. No.5,527,112 to Dais et al.; and U.S. Pat. No. 6,032,854 to Greer et al.

One possible use of the resealable, flexible plastic bag is as a packinglist envelope which is commonly used by courier services such as FedEx,U.S. Postal Service, etc. When a package is sent through the courierservice, a list of the contents of the package, addresses of theaddressee and sender, and various other pertinent information are placedinto a transparent packaging envelope with the addresses visible throughthe front of the envelope. The back of the envelope is then attached tothe package with an adhesive. Because, during the package processing,the envelope is subject to being opened and resealed for placing orremoving items in the envelope, it is desirable to have an envelope thatcan repeatedly be opened and resealed without losing its integrity.

Thus it is desirable to avoid the problems of the prior art envelopesand provide a packing slip envelope that is resealable without damagingthe integrity of the envelope and without the high cost.

SUMMARY OF THE IVENTION

One aspect of the invention is related to a packing slip envelope thatis resealable with an resealable adhesive without damaging the integrityof the envelope. If the packing slip envelope to be attached to apackage, an adhesive preferably permanent is provided on the back of theenvelope. The envelope comprises a front sheet, a back sheet, and aclosure flap. The front sheet has the same width as the back sheet and ashorter height. The back and front sheet are attached at theirrespective side edges and bottom edges via heat sealing. The closureflap attaches to the back sheet at their respective top edges via apermanent adhesive and overlaps the front sheet. To seal the envelope, aresealable adhesive is placed on the outside and adjacent to the topedge of the front sheet. The adhesive binds the closure flap overlap tothe front sheet to seal the envelope. The permanent adhesive used tojoin the closure flap to the back sheet allows the envelope to be openedand resealed without damaging the several joints at the edges of theenvelope. The envelope is preferably made of a plastic and can be eithertransparent or translucent. Printing can be provided on the face sheetor backing sheet.

Another aspect of the invention is related to the method of making thepacking slip envelope.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing background and summary, as well as the following detaileddescription of the drawings, will be better understood when read inconjunction with the appended drawings. For the purpose of illustratingthe invention, there is shown in the drawings embodiments which arepresently preferred. It should be understood, however, that theinvention is not limited to the precise arrangements andinstrumentalities shown. In the drawings:

FIG. 1 depicts a front view of a prior art packing slip envelope havinga resalable adhesive in the open position.

FIG. 2 depicts a front view of a prior art packing slip envelope havinga ziplock seal in the closed position.

FIG. 3 depicts a front view of the present packing slip envelope in theopen position.

FIG. 4 depicts a side view of the present packing slip envelope in theclosed position.

DETAILED DESCRIPTION OF THE DRAWINGS

In the drawings, like numerals are used to indicate like elementsthroughout. Certain terminology is used for convenience only in this andis not limiting. The words “top,” “bottom,” and “side” designatedirections in the drawings to which reference is made.

One possible packing list envelope is depicted in FIG. 1, showing anenvelope made of a heat sealable plastic material having a back sheet102, a front sheet 104, and a closure flap 106. The back sheet 102 andthe front sheet 104 are attached at their respective sides edges 108 and110 and bottom edges 112 via heat sealing resulting in heat seal lines114, 116 and 118. The front sheet also contains a strip of resealableadhesive 120 on the front sheet. The closure flap 106 is attached to theback strip at their respective top edges 122 via heat sealing resultingin heat seal line 124. The closure flap 106 also overlaps the frontsheet 104 such that the resealable adhesive strip is able to attach theclosure flap 106 to the front sheet when the flap is in contact with thefront sheet.

The main drawback of the envelope of FIG. 1 is the relative weakness ofthe heat seal joint of the closure flap to the back sheet. Typically,the opening of the envelope at the closure flap requires a force thatresults in a partial tear of the joint between the closure flap and theback sheet. This is due to the inherent inability of the heat seal jointto withstand the sudden force required to open the resealable adhesiveclosure.

In an attempt to solve the weak heat seal joint, the envelope shown inFIG. 2 is developed. FIG. 2 shows an envelope with a back sheet (notshown), front sheet 204, and closure flap 206. The back sheet and thefront sheet 204 are attached at their respective sides edges 208 and 210and bottom edges 212 via heat sealing resulting in heat seal lines 214,216 and 218. The closure flap 206 is attached to the back strip at theirrespective top edges 222 via heat sealing resulting in heat seal line224. The closure flap is also attached to the front sheet by heatsealing the ends 230 and 232 of the zip lock 220. In effect, thisenvelop is similar to the one depicted in FIG. 1, except that theresealable closure is of the ziplock type rather than a resealableadhesive. A major disadvantage of the ziplock type envelope is highcost, particularly the high cost of producing the ziplock, when comparedto the resealable adhesive envelope.

FIG. 3 shows a front view and FIG. 4 shows a side view of a preferredembodiment of the instant invention. In this preferred embodiment, theenvelope is at least partially made of a transparent (or translucent),flexible plastic such as polyethylene or polypropylene. The inventiveenvelope comprises three sheets of plastic, a back sheet 302, a frontsheet 304, and a closure flap 306, where at least the front sheet istransparent (or translucent). The back sheet 302 and the front sheet 304are joined at their respective side edges and bottom edges. The closureflap and the back sheet are joined at their respective top edges 322 viaa permanent adhesive 340. The closure flap overlaps the front sheet andforms a closure when the closure flap attaches to the front sheet via astrip of resealable adhesive 320. The closed bag can be opened bybreaking the seal between the closure flap 306 and the front sheet 304along the resealable adhesive strip 320. And the bag can be resealed bycontacting the flap 306 and the front sheet 304 and applying pressurealong the adhesive strip 320.

Most preferably, the joint of the front sheet to the back sheet isaccomplished through heat sealing. Generally, this involves aligning theoverlapping edges of the plastic sheets being sealed and applyingpressure adjacent to the edges-with a heated element which melts theplastic and welds the plastic sheets together. Various machines forperforming heat sealing operated by means of AC or DC power areavailable commercially through companies such as Accu-Seal Corporation,San Marcos, Calif. U.S. Pat. No. 5,142,123 to Chou discloses a heatsealing machine appropriate for the instant application.

The resealable adhesive 320 of the present invention may be made of, forexample, pressure-sensitive adhesive material or contact adhesivematerial. Preferably, the closures of the present invention are usefulwith adhesive systems such as pressure-sensitive adhesive materialsincluding acrylic, natural and synthetic rubber types. Adhesives havinggood peel strength are also preferred. Further, it is preferable thatthe force required to separate the closure flap from the front sheetalong the resealable adhesive strip 320 does not damage or cause tearingof the plastic.

Generally, resealable adhesive has some tack but can be opened andclosed repeatedly and leaves no residue. Common examples of resealableadhesives are the adhesive used on Post-it® notes and Craig-Stick®.Resealable adhesives of various level of peel strength and tack orresidue are available commercially.

The resealable adhesive is preferable disposed as a strip as shown inFIG. 3. The strip preferably has a width of about 0.1 to 0.8 inches.However, other pattern may also be used without affecting the invention.These other pattern may be dots, multiple thin strips, etc.

The permanent adhesive 340 can be any permanent adhesive commonly used.The main property that distinguishes the permanent adhesive 340 from theresealable adhesive is that once the bond of the permanent adhesive 340is broken, it cannot further function as an adhesive; i.e., it's notresealable. Further, the bond strength of the permanent adhesive 340 ispreferably much higher than that of the resealable adhesive 320. As amatter of fact, a significant property of the permanent adhesive 340 isthat it can absorb the force required to open the resealable adhesive320 without failure, separating, or pealing. Preferred permanentadhesive includes acrylic adhesives and hot melt adhesives. A backingadhesive 350 can be provided which is preferably permanent to permit theresealable envelope to be attached to a package or other shippingcontainer. The envelope can be printed either on the front sheet 304,flap 306 or back sheet 302.

The invention has been disclosed broadly and illustrated in reference torepresentative embodiments described above. Those skilled in the artwill recognize that various modifications can be made to the presentinvention without departing from the spirit and scope thereof.

What is claimed is:
 1. A resealable envelope comprising a flexible plastic back sheet; a backing adhesive applied on a back surface of said flexible plastic back sheet to attach the envelope to a package; a flexible plastic front sheet, said front sheet and said back sheet attaching at their respective side edges and bottom edges; a flexible plastic closure flap, said closure flap being adhered directly to a front surface of said back sheet at their respective top edges via a permanent adhesive, said closure flap overlaping said front sheet; and a resealable adhesive locating proximal to the top edge of said front sheet such that said resealable adhesive is capable of fastening said closure flap to said front sheet forming a resealable closure.
 2. The resealable envelope of claim 1, wherein the front sheet and back sheet are attached via heat sealing.
 3. The resealable envelope of claim 1, wherein said resealable adhesive is a pressure-sensitive adhesive.
 4. The resealable envelope of claim 1, wherein said resealable adhesive is disposed as a strip proximate to the top edge of the front sheet.
 5. The resealable envelope of claim 1, wherein the permanent adhesive is a an acrylic adhesive.
 6. The resealable envelope of claim 1, wherein the flexible plastic is polyethylene or polypropylene.
 7. The resealable envelope of claim 1, wherein the permanent adhesive can absorb a force required to open the resealable adhesive without failure.
 8. The resealable envelope of claim 1, wherein the flexible plastic front sheet is transparent.
 9. A method of making a resealable envelope, said method comprising providing a front sheet, a back sheet, and a plastic closure flap; attaching said front sheet to said back sheet at their respective side edges and bottom edges; attaching said closure sheet directly to a front surface of said back sheet at their respective top edges via a permanent adhesive, said top sheet overlapping said front sheet; providing a resealable adhesive proximal to the top edge of said front sheet such that said resealable adhesive is capable of removably fastening said closure flap to said front sheet; and providing a backing adhesive on a back surface of said back sheet for attaching the resealable envelope to a package.
 10. The method of claim 9, wherein the front sheet and back sheet are attached via heat sealing.
 11. The method of claim 9, wherein said resealable adhesive is a pressure-sensitive adhesive.
 12. The method of claim 9, wherein said resealable adhesive is disposed as a strip proximate to the top edge of the front sheet.
 13. The method of claim 9, wherein the permanent adhesive is an acrylic adhesive.
 14. The method of claim 9, wherein the flexible plastic is polyolefin.
 15. The method of claim 9, wherein the permanent adhesive is capable of absorbing a force required to open the resealable adhesive without failure.
 16. The method of claim 9, wherein the flexible plastic front sheet is transparent.
 17. A resealable envelope comprising a flexible plastic back sheet; a backing adhesive on a back surface of said back sheet for attaching the envelope to a package; a transparent and flexible plastic front sheet, said front sheet and said back sheet attaching at their respective side edges and bottom edges via heat sealing; a resealable adhesive strip locating proximal to the top edge of said front sheet; and a flexible plastic closure flap, said closure flap being adhered directly to a front surface of said back sheet at their respective top edges via a permanent adhesive, said closure flap overlaping said front sheet such that said resealable adhesive strip is capable of fastening said closure flap to said front sheet forming a resealable closure, said permanent adhesive is capable of absorbing a force required to open the resealable adhesive without failure.
 18. The resealable envelope of claim 17, wherein the plastic back sheet is printable or tinted.
 19. The resealable envelope of claim 17, wherein the plastic front sheet is printable or tinted.
 20. The resealable envelope of claim 17, wherein the plastic closure flap is printable or tinted. 